Many cheetahs being raised in troops in Japanese zoos are dying of amyloidosis, a protein abnormality that may be in part stress-related, a research team at Azabu University said Monday.

News photoCheetahs lounge at a Japanese zoo in this undated file photo taken by Azabu University researcher Yumi Une. PHOTO COURTESY OF AZABU UNIVERSITY

Amyloidosis is a condition characterized by abnormal protein deposits accumulating in internal organs.

The incidence of death among cheetahs is higher for those being raised in bigger groups, said Yumi Une, an assistant professor of veterinary science at the university in Kanagawa Prefecture and the head of the study.

She said the team believes the risk of suffering amyloidosis is being heightened because cheetahs, which live a solitary life in the wild, are experiencing stress from being bred in groups and are exposed to amyloids included in their excrement.

"Amyloids, which are abnormal proteins, are deposited in the liver, the kidneys or the intestines and cause conditions such as dysfunction," Une said.

Amyloidosis, which can occur in humans and other animals, is a disorder characterized by the deposit of amyloids in organs and tissues, and causes dysfunction in the affected body parts. It includes Alzheimer's disease and Creutzfeldt-Jakob disease.

The team analyzed the approximately 180 cheetahs that have died since 1985 at nine facilities, including zoos and safari parks, and found that the average life span grew shorter as the number of cheetahs being bred together increased.

While there was no correlation with respect to the size of breeding area or their feed, amyloid deposition was observed in the kidneys, liver and other organs of 57 of every 60 cheetahs that died, according to the team.

The total number of cheetahs being bred in Japan decreased to 50 in 2003 from about 90 in 1995, the team said.

"There are no other animals that have such a high incidence of amyloid deposition," Une said. "I think (the study on cheetahs) will serve as a reference for research on diseases among humans caused by amyloids."

The research team will announce its findings at a meeting of the Japanese Society of Veterinary Science scheduled to begin Tuesday in Wako, Saitama Prefecture.